Gentoo GURU emerge: add --autounmask=y to handle ~amd64 keyword

The GURU emerge in run_once_20-install-user-packages-gentoo.sh.tmpl
was missing --autounmask=y (only had --autounmask-license=y). Same
fix as the main pkg loop: GURU packages like dev-vcs/lazygit are
~amd64-only and need the keyword unmask to be auto-written.

Symptom: 'The following keyword changes are necessary to proceed:
=dev-vcs/lazygit-0.62.2 ~amd64' even though --autounmask=y was
already on the main pkg loop. Fix: add the same flag to the GURU loop.

run_once_20-install-user-packages-gentoo.sh.tmpl

@@ -139,8 +139,11 @@ if (( ${#MISSING_PKGS[@]} > 0 )); then
     # --quiet-build: only show errors during compile
     # --keep-going: don't abort if one package fails
     # --with-bdeps=y: include build deps so we don't accidentally skip them
+    # --autounmask=y: auto-write ~amd64 keyword unmask files (lazygit
+    #   is ~amd64 only)
+    # --autounmask-license=y: auto-accept license unmask
     sudo emerge --ask=n --nospinner --quiet-build --keep-going \
-        --with-bdeps=y --autounmask-license=y \
+        --with-bdeps=y --autounmask=y --autounmask-license=y \
         "${MISSING_PKGS[@]}"
 else
     log "all user packages already installed; skipping emerge"
@@ -180,7 +183,7 @@ done
 if (( ${#GURU_MISSING[@]} > 0 )); then
     log "emerge GURU packages (missing: ${GURU_MISSING[*]})"
     sudo emerge --ask=n --nospinner --quiet-build --keep-going \
-        --with-bdeps=y --autounmask-license=y \
+        --with-bdeps=y --autounmask=y --autounmask-license=y \
         "${GURU_MISSING[@]}"
 fi
 

run_once_40-install-sway-gentoo.sh.tmpl

@@ -71,7 +71,7 @@ if (( ${#MISSING_PKGS[@]} > 0 )); then
     log "missing: ${MISSING_PKGS[*]}"
     log "emerge sway stack (gentoo compiles from source; this may take a while)"
     sudo emerge --ask=n --nospinner --quiet-build --keep-going \
-        --with-bdeps=y --autounmask-license=y \
+        --with-bdeps=y --autounmask=y --autounmask-license=y \
         "${MISSING_PKGS[@]}"
 else
     log "all sway packages already installed; skipping emerge"